Various fire retardants are known for certain applications. For instance, compositions are known, which typically contain fire suppressing salts such as an ammonium phosphate or ammonium sulphate, for aerial application to combat forest fires. See, U.S. Pat. Nos. 3,196,108; 3,257,316; 3,309,324; 3,634,234; 3,730,890; 3,960,735; 4,447,336; 4,447,337; 4,606,831; 4,822,524; 4,839,065; 4,983,326 and 6,162,375. Other compositions are known to contain other fire suppressants such as carbonaceous matter, organic phosphorous compounds, organic halides, or borates. See, U.S. Pat. Nos. 4,668,710; 4,686,241; 5,246,652; 5,968,669; 6,001,285; 6,025,027; 6,084,008 and 6,130,267.
As can be appreciated, in addition to fire retardants used to combat forest fires, intended as a temporary measure to be washed away with rain once the fire threat is minimized, prevention of the spread of fire is an important consideration sought in many everyday materials and construction applications such as paper, wood, fabric and many plastics. As such, much research has been conducted to determine how to reduce or eliminate the potential fire hazards caused by such materials.
In general, all organic and some inorganic materials will burn under appropriate conditions. With solid materials, this involves decomposition of the solid to produce gases which burn, rather than combustion of the solid per se. Actual burning of an item occurs in four main stages: 1) heating: an ignition source raises the temperature of the item; 2) decomposition: when sufficiently heated, the item begins to change its properties and break down, forming combustible gases; 3) ignition: combustible gas production increases until a concentration is reached that allows for sustained, rapid oxidation when exposed to an ignition source; and 4) combustion and propagation: combustion of the gases becomes self-propagating if the heat generated is sufficient to be radiated back to the item and continue the heating and decomposition steps.
Decades ago, most home furnishings were made from natural materials including wool, cotton and horse hair, which were relatively flame resistant; so, if a fire started in the home, it would generally take some eight to ten minutes before flash-over would occur, depending on a fire's location, and availability of flammable materials in close proximity to the source of the fire. If discovered quickly enough, the fire department would arrive to extinguish the blaze before it grew too rapidly and flash-over occurred. Flash-over, of course, occurs when the rate of combustion and flame spread in the dwelling becomes so rapid that the air becomes super heated, which causes all exposed flammable surfaces to erupt into flames, i.e., “flash over.” This produces the equivalent of an explosion, blowing out doors and windows, and causing serious bodily injury or death. Now, however, most everyday household materials are extremely flammable themselves, being made not only of paper and wood but also synthetic fabric and plastic, the latter, of course, made from petroleum products. Thus, flash-over is of increasingly serious concern, and the time it takes for the modern untreated materials to flash-over has significantly decreased. Some of the modern materials may practically burst into flames with a short exposure to the ignition source, and flash-over may occur before the fire department can get to the home, even if notified promptly. As can readily be appreciated, therefore, the residential fires of today can be most tragic when compared to those of past years.
In addressing the same, conventional intumescent systems have been developed. They typically include as essential components 1) an acid-forming substance; 2) an expanding agent, which causes formation of a foamed (intumescent) layer by emission of an inert or non-combustible gas, referred to as a “spumific”; and 3) a binder such as a thermoplastic resin, which contributes to film-forming properties of the system and provides a portion of a char skeleton, and which is referred to as a “carbonific.” A component may have more than one function. Typical state of the art conventional phosphate-catalyzed intumescent compositions can be composed of components selected from among the following:                1. As the acid source (catalyst), usually amino phosphates, mainly ammonium polyphosphates, ammonium orthophosphate, and melamine phosphate, say, in an amount of about 25% by weight of the total formulation.        2. As the spumific, melamine, melamine salts, melamine derivatives, urea and/or dicyandiamide.        3. As the carbonific, polyhydroxy compounds, usually a polyol, which is decomposed by liberated phosphoric acid to form an ester which results in formation of the char (carbonification), for example, pentaerythritol, dipentaerythritol, tripentaerythritol, or certain sugars, starches or starch derivatives.Two disadvantages with the conventional systems are cost and opacity. Opaque compounds such as ammonium polyphosphate in powder form, powdered amines and carbonific components are often employed. These tend to be not only expensive, owing to the materials and their labor-intensive production, but also less desirable aesthetically, say, on woodwork where its exposed surface is sought after as an architectural feature.        
Also, many conventional fire retardant compositions utilize non-biodegradable ingredients. These may pose a threat to the health of an applicator or occupant, or to the environment.
It would be desirable to ameliorate if not completely overcome one or more of such problems.